Peters-plus syndrome (PPS) is a variable complex disorder with autosomal recessive inheritance. The following features are commonly seen in PPS: ocular anterior segment defects, short stature, brachydactyly, cleft lip and/or cleft palate, various craniofacial defects, and brain, heart, as well as genitourinary anomalies. PPS syndrome was recently discovered to be caused by mutations in the B3GALTL gene that encodes a glycosyltransferase. Glycosyltransferases are known to play important roles in various biological processes, and represent enzymes that catalyze the attachment of a sugar molecule to specific acceptor sites. Patients with PPS have two mutated alleles of B3GALTL, typically either a complete deletion of the gene or nucleotide changes predicted to result in a truncated protein lacking its catalytic domain. B3GALTL mutations appear to explain the majority of classic PPS, but no mutations in this gene have been identified in human patients with highly similar disorders. At this time, the developmental mechanisms of PPS and related conditions are not known, and no animal models have been established for B3GALTL-deficiency/PPS. The investigator's preliminary studies have identified two b3galtl genes in the zebrafish that demonstrate expression patterns and knockdown phenotype (for b3galtlb) consistent with PPS features in humans. Since PPS is characterized by a highly variable phenotype, generation of the zebrafish model of PPS is essential to genetic dissection of this disease and identification of additional causative or modifying loci/genes. In this application, she plans to focus, in Specific Aim 1, to determine the functional sequences and expression patterns of zebrafish b3galtl genes, which involves characterization of transcripts, genomic structures, functional regulatory regions, and expression patterns of the b3galtl genes;and in Specific Aim 2, to examine phenotypes associated with deficiency for the b3galtl genes through analyses of morpholino-mediated single as well as double gene knockdowns. Generation of zebrafish lines via zinc-finger nuclease technology will be initiated for gene(s) that demonstrate a robust phenotype to create vertebrate model(s) to study the complex and variable features associated with B3GALTL/b3galtl deficiency. NARRATIVE: Peters-plus syndrome (PPS) is a complex disorder that involves abnormal development of the eye, head, brain, hands, heart, kidney, and stature. Mechanism(s) of PPS and related debilitating conditions are largely unknown. Mutations in B3GALTL gene were shown to explain a significant portion of patients with these phenotypes. Studies in animal models can provide a better understanding of underlying developmental mechanisms and involvement of additional factors. In this application, a classic vertebrate developmental model, zebrafish, will be explored to gain insight into developmental processes associated with orthologous b3galtl genes in zebrafish to better understand mechanisms of PPS and related conditions in humans.